240 TUBERCULOSIS. 



It is impossible to speak definitely on the question at present. 

 We can only say that the younger bacilli stain uniformly, and 

 that in the older forms inequality in staining is met with, but it 

 has not been proved that this indicates spore formation. 



The bacilli in the tissues occur scattered irregularly or in 

 little masses. They are usually single, or two are attached end 

 to end and often form in such a case an obtuse angle. True 

 chains are not formed, but occasionally short filaments are 

 met with. In cultures the bacilli form masses in which the 

 rods are closely applied to one another and arranged in a 

 more or less parallel manner. Tubercle bacilli are quite devoid 

 of motility. 



Aberrant Forms. Though such are the characters of the 

 organism as usually met with, other appearances are sometimes 

 found. In old cultures, for example, very much larger elements 

 may occur. These may be in the form of long filaments, which 

 may be swollen or clubbed at their extremities, may be irregularly 

 beaded, and may even show the appearance of branching. Such 

 forms have been studied by Metchnikoff, Maffucci, Klein, and 

 others. Their significance has been variously interpreted, for 

 while some look upon them as degenerated or involution forms, 

 others regard them as indicating a special phase in the life history 

 of the organism, allying it with the higher bacteria. Recent 

 observations, however, go to establish the latter view, and this 

 is now generally accepted by authorities. It has also been 

 found that under certain circumstances tubercle bacilli in the 

 tissues produce a radiating structure closely similar to that 

 of the actinomyces. This was found to be the case by Babes 

 and also by Lubarsch, when the bacilli were injected under 

 the dura mater and directly into certain solid organs, such as 

 the kidneys in the -rabbit. Club-like structures are also present 

 at the periphery ; these are usually not acid-fast, but they 

 retain the stain in the Weigert-Gram method. Similar results 

 have also been obtained with other acid-fast bacilli, which 

 will be mentioned below, and these would appear to form a 

 group of organisms closely allied to the streptothriceae, the 

 bacillary parasitic form being one stage of the life history of 

 the organism. 



Staining Reaction. The tubercle bacillus takes up the 

 ordinary stains very slowly and faintly, and for successful staining 



